The goal of this project is to isolate a specific DNA of mRNA using oligodeoxyribonucleotide probes whose sequences are predicted from the amino acid sequence of a specific protein. More specifically: a) We shall screen the cloned cDNA for human beta 2-microglobulin and mouse major histocompatibility antigen H-2Kb by the synthetic mixed probes to establish the screening method to isolate a specific gene. b) We shall synthesize the mixed probes for the isolation of cDNA for mouse PGK and RGPTase. c) We shall begin work on the isolation of a specific mRNA using the synthetic oligonucleotides on a solid phase as a probe.